The researchers found a mix of factors that may contribute to people becoming FTFs.

They were often young, male, lacked a good education with poor job prospects, and from dysfunctional families in urban settings.

Personal and social networks played a role in motivating the FTFs to travel to warzones, while religious beliefs and ideology were less influential. FTFs were sometimes motivated by the perception of persecution to community groups they associated with.

The report states that FTFs were encouraged to return home by the ‘disappointment and disenfranchisement’ with the terrorist groups they joined.

Interviews

Prof El-Said, Professor of International Business and Political Economy at Manchester Metropolitan, said: "It is one of the few reports that is based on direct and face-to-face interviews with former or would-be FTFs.

"It therefore investigates the motivations for individuals not only to depart and join transnational terrorist organisations in conflict zones like Syria and Iraq, but also to defect from such organisations and regions thereafter. This is done from the point of view of FTFs themselves.

"It documents motivations of FTFs, their narratives, and stories using their own words and accounts.

"It is based on the largest known sample of face-to-face interviews with such groups and individuals.

Policy implications

"Contrary to conventional wisdom, the report finds ideology and religion to be less influential than socio-economic and political factors are in motivating individuals to join transnational terrorist organisations like ISIS or al-Qaida in conflict zones.

"This finding has significant policy implications."

Prof El-Said carried out the study with co-author Richard Barrett, a former intelligence officer turned global terrorism expert, for the UN Office of Counter-Terrorism.